Loop height adjusting device for a supersonic wire bonder

ABSTRACT

A loop height adjusting device for a supersonic wire bonder, which comprises a cam profile for the first search level and a cam profile for adjusting a loop height fixed on separately disposed cams respectively to adjust the loop height irrespective to a presettled value of the first search level by choice of configuration of the cams, so that the adjustment of the loop height can be attained easily and optionally using an adjust screw, thus eliminating troublesome replacements of cams.

United States Patent [191 Isobe LOOP HEIGHT ADJUSTING DEVICE FOR A SUPERSONIC WIRE BONDER [75] Inventor: Masahide Isobe, l-layamamachi,

Japan [73] Assignee: Tokyo Sokuhan Kabushiki Kaisha,

Hayamamachi, Japan [22] Filed: June 21, 1973 [21] Appl. No.: 371,964

Related US. Application Data [63] Continuation of Ser. No. 141,208, May 7, i971,

abandoned.

[52] US. Cl 228/1, 29/4703, 74/55, 228/3, 228/4 [51] Int. Cl B23k 5/20 [58] Field of Search 228/1, 3, 4; 29/4701, 29/4703; 74/55 [56] References Cited UNITED STATES PATENTS 3,305,157 2/1967 Pennings 228/1 LOOPx HIGHT 111 3,819,102 [451 June 25, 1974 3,342,395 9/1967 Diepeneen 228/1 3,543,988 12/1970 Kulicke, Jr... 228/3 3,601,304 8/1971 Mansour 228/1 Primary Examiner-J. Spencer Overholser Assistant Examiner-Robert J. Craig Attorney, Agent, or Firm--Toren and McGeady [5 7] ABSTRACT 1 Claim, 8 Drawing Figures II 0 I PATENTEB $819,362

CAM PROFILE FOR I3 I I2 I O FIRSTSEARCH LEvEL ifl 9 HIGHT l5 Io- CIT.

Q I'fF/I E CAM PROFILE FOR I' LOOP HEIGHT FIG. 3

L BONDING suREAcE I YNVENTOR.

PATENIEUJUNZEIW I 3.819.102

sum 2 0r 4 4 5 2l-\ 7 FIG. 5

IIIIIII AIIIIIIII BONDING T suRFAcE CAM PROFILE FOR FIRST SEARCH LEVEL IINVENTOR.

' MASAHIDIE 15005 Emzwo flf ATTOIQN 5 PATENIED 5 I974 3.819.1U2

sum 3 or 4 LOOP HEIGHT FIG. 7

INVENTOR.

NASA HIDE ISOB PAIENIEDMZSIBH 4 3.819.102

- CAM PROFILE FOR F ST SEARCH LEVEL FIRST BONDING INVENTOR.

MAsAHmE 15055 BY Team MW LOOP HEIGHT ADJUSTING DEVICE FOR A SUPERSONIC WIRE BONDER This is a continuation of application Ser. No. 141,208, filed May 7, 1971 now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to a loop height adjusting device for a supersonic wire bonder.

Various kinds of integrated circuits (1C) have been adopted in order to keep pace with rapid increase of electronic computers, desk computers, radio sets and televisions in the integrated circuit manufacturing industry. However there have been drawbacks such as poor yield of product caused by unexpected hitch of contacting wires, since every individual distance or height of fusion welding points are different from one another in the constitution of circuits. In attempts to overcome the foregoing drawbacks and to increase efficiency in manufacturing, adjustment of the loop height has been urgently sought.

The present invention solves the foregoing drawback advantageously.

A wire bonder is an apparatus for fusion welding of an electrode on a die 1 with a point on a substrate or a terminal 2 using a wire 3 as shown in FIG. 1. It is desirable to adjust the loop height shown in FIG. 1 in correspondence to the difference of distance or height of the foregoing two fusion welding points.

Up to this day, an adjusting means for a widely popular type of cam mechanism known as a supersonic wire bonder is usually provided with an adjusting means for the first and the second search levels. And similar adjusting means (not shown in the drawings) is provided on a supersonic wire bonder having loop height adjust ing means according to the present invention. However, the conventional wire bonder is not provided with loop height adjusting means, but cam profiles for the first search level and for loop height adjustment are provided on the outer periphery of a single cam so that the loop height is automatically set by the setting of the first search level. Therefore, the conventional device has a drawback such as a troublesome operation of replacing of a cam having cam profile corresponding to a desired loop height for a certain preset value of the first search level.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an explanatory sketch showing the operation of the wire bonding operation.

FIGS. 2, 3 and 4 are respectively schematic drawings of a supersonic wire bonder provided with a loop height adjusting means according to the present invention, showing essential parts of said wire bonder in a form of an embodiment and FIG. 2 is a side view of a cam mechanism provided with a cam profile for the first search level, showing the operation of the first search level in cyclic motion, FIG. 3 is a side view of a cam mechanism provided with a cam profile for adjusting loop height, showing the operation of cyclic motion thereof for adjusting loop height and FIG. 4 is a front view of the cam mechanism shown in FIGS. 2 and 3 respectively.

FIGS. 5, 6 and 7 are schematic drawings respectively of a supersonic wire bonder provided with a loop height adjusting means according to the present invention, showing essential parts of the wire bonder in a form of another embodiment and each of FIGS. 5, 6 and 7 are side views and a front view of the cam mechanism, showing the operation thereof corresponding to FIGS. 2, 3 and 4.

FIG. 8 is a side view of the two cam mechanisms disposed in parallel with each other, showing the configuration of each cam.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to theembodiment shown in FIGS. 2, 3 and 4, a capillary 4 is fixed to a horn 5 at the left end thereof, a horn holder 6 holding said horn 5 is pivotally hinged by a shaft 7, a plate 8 is fixed to said holder 6 at the right end thereof, the upper end of said plate 8 is engageable with a roller 11 fixed to the lower end of a lever 10 hinged by a pivot 9 to which is hinged a bellcrank 12 provided with a roller 13 at the right end and a screw 14 at the lower end thereof respectively. The roller 13 corresponds to the other periphery of a cam 16 pivotted to the cam shaft 15, said outer periphery being provided with a cam profile the first search level.

The front end of the screw 14 is engageable with said lever 10, and the pivot 9 is hinged with the other bellcrank 17 with a roller 18 at the right end and an adjust screw 19 at the lower end thereof respectively. The roller 18 corresponds to the outer periphery of a cam 20 pivotted to said cam shaft 15 in parallel with said cam 16 said outer periphery having a cam profile for adjust ing loop'height. The front end of the adjust screw 19 is engageable with the lever 10.

Upon starting the rotational movement of the cams 16 and 20about the cam shaft 15 the roller 13 is driven by the outer periphery of the cam 16 corresponding to the contour of these cam profiles, and thus the bellcrank 12 is actuated to be in rocking motion about the pivot 9 causing the lever 10 to be pushed by the front end of the screw 14. When the roller 18 is driven the outer periphery of the cam 20, the bell-crank 17 is subjected to rocking motion about the pivot 9 causing the rocking movement of the lever 10 pushed by the front end ofthe screw 19, thereby the capillary 4 is caused to move up and down through the roller 11 provided at the lower end of said lever 10, the plate 8 contacting the roller 11, the horn holder 6, and the born 5 respectively.

As the result, the height from the bonding surface formed at the front end of said capillary 4 is subjected to vary corresponding to the predetermined cyclic motion.

In the aforementioned cyclic motion, it depends upon the present position and the contour of profile of the cams l6 and 20 and the screw 14 as well as the adjusted position of the adjust screw 19 whether the roller 13 is driven by the outer periphery of the cam 16, or the roller 18 is driven by the outer periphery of the cam 20, so that provided that the earns 16 and 20 have such a form of the profile, for example as shown in FIG. 8 i

that the roller 13 is driven by the cam 16 at the first search level and the roller 18 is driven by the cam 20 at the time of loop height adjustment, and provided that the front end of the screw 14 is set in such a position as to dispose the capillary 4 to be nearly vertical to the bonding surface at the time of the first bonding operation in the course of the foregoing cyclic motion, the loop height a can be adjusted through the adjustment of the adjust screw 19 to any desired value within a range hereinafter described in response to a certain preset value of the first search level.

In respect to the two cams l6 and 20 shown in FIG. 8, the cam profile for the first search level and the cam profile for adjusting loop height are positioned at the same distance from the axis of the cam shaft 15, so that, in case the rollers 13 and 18 are located at the equal height when the screw 14 and the front end of the adjust screw 19 come in contact with the lever 10 respectively, that is, when the adjust screw 19 is adjusted to the value b in respect to the foregoing positioning of the front end of the screw 14, the loop height a and a certain preset value of the first search level become equivalent to each other, thereby the adjust screw 19 is screwed in furthermore to increase the value b increasing the value of the loop height a. In this case adjustment of the adjust screw 19 can be carried out optionally within the range until the difference b in height between the rollers 13 and 18 becomes equal to the difference 0 in distance from each of the outer peripheries of the cams 16 and 20 locating at the position of the first search level respectively to the axis of the cam shaft 15, so that within the above range the loop height a is adjusted against a certain presettled value a of the first search level corresponding to the adjustment of the adjust screw 19 to adjust the loop height shown in FIG. 1. In case the value b is more than the value 0 beyond the aforementioned range, the roller 13 does not come into contact with the cam 16 even when the first search level and cyclic motion is actuated by the contact of the roller 18 and the cam 20 with each other, the first search level as well as the loop height are determined by a single cam 20 only. Accordingly, when the first search levelv is set, the loop height is automatically determined, and thus adjustment of the loop height in correspondence to a certain preset value of the first search level can not be effected. The screw 14 may be omitted by constituting the lever to be integral with the bell-crank 12.

Now the supersonic wire bonder according to the present invention will further be explained in connection with embodiments shown FIGS. 5, 6 and 7, wherein a capillary 4 is fixed to a horn 5 at the left end thereof, a horn holder 21 holding the horn 5 is hinged to a shaft 7, at the lower part of the horn holder 21 is provided with a pivot 22 to which is hinged a lever 23 having a screw 14 at the upper end and a roller 13 at the lower end thereof respectively. The roller 13 corresponds to the outer periphery of a cam 16 pivotted to a cam shaft 15, said outer periphery having a cam profile for the first search level while the front end of the screw 14 engages with the bottom of a groove which accommodates therein the lever 23 pivotted to the horn holder 21. Another lever 24 is hinged to the pivot 22 and is provided with an adjust screw 19 at its upper end and a roller 18 at its lower end respectively. The roller 18 corresponds to the outer periphery of a cam 20 pivotted to the cam shaft to be in parallel with said cam 16, said outer periphery having a cam profile for the loop height, while the front end of the adjust screw 19 engages with the bottom of a groove which accommodates therein the other lever 24 pivottally fixed to the horn holder 21.

When the cams l6 and 20 rotate about the cam shaft 15, the horn holder 21 is actuated to start the rocking motion through the lever 23 and the screw 14 in case the roller 13 is driven by the outer periphery of the cam 16 or through the lever 24 and the adjust screw 19 in case the roller 18 is driven by the outer periphery of the cam 20 corresponding to the cam profiles of the foregoing cams l6 and 20, thereby causing up and down movement of the capillary 4 fixed to the horn 5 at its left end holded by the horn holder 21, and also causing variation of height from the bondingsurface formed at the front end of the capillary 4 corresponding to the predetermined cyclic motion. Accordingly, when the cams 16 and 20 are formed with the cam profile as shown in FIG. 8 and is set in such a position of the front end of the screw 14 as to dispose the capillary 4 to be nearly vertical to the bonding surface in a similar way as in the embodiment shown in FIGS. 2, 3 and 4, the loop height is adjusted corresponding to adjustment of the adjust screw 19 in a similar way as in the embodiment shown in FIGS. 2, 3 and 4. In addition, the screw 14 may be omitted by constructing the lever 23 integral with the horn holder 21.

According to the above-mentioned construction of the present invention, adjustment of the loop height will easily and optionally be effected by means of an adjust screw and it is remarkably effective for manufacturing integrated circuits (IC) and the like.

What is claimed is:

1. Apparatus for positioning a work too] relative to a workpiece in a supersonic wire bonder comprising;

a work tool holder;

means for pivotally mounting said holder;

an arm fixed to said holder for enabling pivotal motion thereof about said mounting means;

a pair of cam follower members each having a first and a second end and each member being pivotally mounted at a point intermediate said ends;

a cam follower mounted at each of said first ends of said cam follower members;

a pair of cams mounted for simultaneous rotation and each including a cam profile means located to be individually engaged, respectively, by one of said cam followers;

engagement means for enabling contact individually between each of said second ends of said cam follower members and said work holder arm to effect movement of said arm by each of said cam follower members in accordance with the respective contours of said cam profile means;

said engagement means including means for individually adjusting the point of contact between each of said second ends of said cam follower members and said work holder arm, said adjustment means being individually operatively associated, respectively, with one of said cam followers to individually determine the point at which either of said cam profile means commences to impart motion to said work holder arm;

whereby the pattern of motion imparted by said cams to said work holder may be individually adjusted for each of said cams. 

1. Apparatus for positioning a work tool relative to a workpiece in a supersonic wire bonder comprising; a work tool holder; means for pivotally mounting said holder; an arm fixed to said holder for enabling pivotal motion thereof about said mounting means; a pair of cam follower members each having a first and a second end and each member being pivotally mounted at a point intermediate said ends; a cam follower mounted at each of said first ends of said cam follower members; a pair of cams mounted for simultaneous rotation and each including a cam profile means located to be individually engaged, respectively, by one of said cam followers; engagement means for enabling contact individually between each of said second ends of said cam follower members and said work holder arm to effect movement of said arm by each of said cam follower members in accordance with the respective contours of said cam profile means; said engagement means including means for individually adjusting the point of contact between each of said second ends of said cam follower members and said work holder arm, said adjustment means being individually operatively associated, respectively, with one of said cam followers to individually determine the point at which either of said cam profile means commences to impart motion to said work holder arm; whereby the pattern of motion imparted by said cams to said work holder may be individually adjusted for each of said cams. 